Snails and slugs aren’t just agricultural and horticultural pests

David G. Robinson Ph.D. USDA APHIS National Malacology Laboratory The Academy of Natural Sciences of Drexel University, Philadelphia, PA 19103 USA  Invasive mollusk species have the potential to:  Introduce snail-vectored human and livestock diseases, including cerebral and abdominal angiostrongyliasis  Introduce these diseases to native species and other invasive species that are already present

 Laboratory studies indicate that diseases such as those that affect recognized vectors (such as GAS and veronicellid slugs) can be introduced into native snail and slug populations, increasing the threat to Public Health

 Facilitate the spread of other diseases not normally associated with mollusks  For example, large accumulations of dead GAS shells filling with rain water can provide an ideal breeding environment for mosquito larvae – producing more mosquitoes and perhaps facilitating the spread of malaria, dengue fever, yellow fever and as of 2015 chikungunya (throughout the West Indies, including the U.S. Virgin Islands), as well as Africa (where it originated)  Plant pathogens such as Phytophtora spp. , not usually associated with molluscs, can also be vectored by snails including GAS

Dead shells along roadside in Barbados (photo: A. Fields)  The association of invasive, synanthropic snails and slugs with human habitation brings snails and slugs, if populations are high enough, into direct contact with people  Directly impact urban and suburban householders, leaving slime trails, piles of feces and dead, rotting snails in homes and gardens  This may also impact tourism  Example: GAS on golf courses, in hotels in hotel gardens, floating dead in swimming pools, etc. in the Antilles  Reports of cases of cerebral angiostrongyliasis in tourists and local people in Jamaica and the Hawaiian Islands is of considerable concern to their governments

Several of the invasive species are known to be vectors of a serious disease that affects humans and livestock, including:  the giant African snail (GAS ) – Lissachatina fulica  the Cuban slug – Veronicella cubensis & other veronicellid species  the Southeast Asian semi-slug – Parmarion martensi  the Asian tramp snail – Bradybaena similaris  the Apple snails – family Ampullariidae – Pomacea sp. & Pila sp.

The disease, known as eosinophilic angiostrongyliasis, is caused by a parasitic nematode worm, Angiostrongylus cantonensis – the Rat Lungworm. It can be contracted by consuming improperly cooked snail meat (in the case of the giant African snail), freshwater crustaceans, or by accidentally ingesting tiny snails, slugs and crustaceans that are infected by the larval cercaria.  Infected snails and slugs can also contaminate water supplies with the nematode if they fall into drinking water, drown and decompose. We now understand that the slime of these gastropods left on uncooked fruits and vegetables may also transmit the disease  Symptoms include severe headaches, nausea, vomiting, neck stiffness, sensitivity to light and contact, seizures, and neurological abnormalities, lasting several weeks  In addition to humans, the disease has also been reported in monkeys, horses, and other livestock. Therefore it has considerable veterinary importance, as well as a public health threat  Death can occur, especially in healthy young adults  Disease prevention relies on handling all snails and slugs with latex gloves, and thorough washing of hands with hot soap and water afterwards Another disease affecting humans, known as abdominal angiostrongyliasis, is caused by a closely related parasitic nematode worm, Angiostrongylus costaricensis. Like cerebral angiostrongyliasis, the slime of these gastropods left on uncooked fruits and vegetables may also transmit the disease  Symptoms include severe lower abdominal pain from infection of the appendix, bowel and colon, with recurrent gastro-intestinal bleeding Sarasinula plebeia from Zamorano, Honduras  Death can rarely occur, and serious complications result if the infected parts are not surgically removed  The disease has been reported from Costa Rica and Brazil, and is probably widespread from Mexico to Argentina. Some cases have been reported from the southern United States

Among the invasive species known to be vectors of this disease include:  Various veronicellid slugs – Sarasinula plebeia (Fischer), Diplosolenodes occidentalis (Guilding), and Belocaulus angustipes (Heynemann)  Some widespread snails including Subulina octona Subulina octona from St. Kitts (Bruguière) and Bradybaena similaris (Férussac) Watch the video: http://animal.discovery.com/vide os/monsters-inside-me-the-rat- lungworm.html

Source: Centers for Disease Control, Atlanta, Georgia, USA

Infected patients at rural clinic in Ecuador

The tradition of making ceviche out of snails in the interior of Ecuador and Colombia, and the recent introduction of GAS in the regions has resulted in hundreds of cases of eosinophilic angiostrongyliasis and numerous deaths

« Adult Angiostrongylias cantonensis taken from the lungs of rats

(photos: L. Robles)  The Rat lungworm is also known to infect domestic livestock and wildlife, including horses (in rural Louisiana), monkeys (New Orleans zoo), apes (orang-utan in a Miami zoo), and is widespread in the Hawaiian Islands  It has recently been reported in southern California (in a captive African pygmy falcon)  Therefore the presence of the nematode in the environment has been confirmed in Florida, Louisiana, California, and Hawaii, and raises the possibility that it will spread into native and invasive snail populations and hence into the local rat populations  Samples of snails and slugs have been taken in the Miami-Dade area, as well as from numerous localities in California  In addition to the giant African snail, another invasive snail, the Cuban snail (Zachrysia provisoria) has been shown to vector the disease in Florida  No positive results have been reported from California Terrestrial and aquatic gastropods are important vectors of disease:  Snails from temperate climates in Europe and Asia transmit a number of (Fasciola and Paragonimus) liver flukes that parasitize livestock, especially chickens, sheep and cattle  Many freshwater species, especially those from subSaharan Africa, and southern and Southeast Asia, transmit schistosome cercaria resulting serious diseases such as Bilharzia or Schistomiasis, affecting the veins of the intestine and bladder. Some of these parasites have been detected in snails in aquarium shipments from Singapore, which exports shipments from all over Southeast Asia, to the rest of the world

 Other terrestrial snails and slugs, especially (but not Biomphalaria species restricted to) tropical and semi-tropical species, are known to vector potentially lethal diseases that affect humans and livestock Discus rotundatus (Müller) Oxychilus draparnaudi A European species, (Beck) Another European established in the USA and species, established in the Canada, is an important USA and Canada, is also vector of Tobacco Mosaic an important vector of Virus Tobacco Mosaic Virus Numerous snail species , Several snail species , including Ponentina including Helicella itala poentina (Morelet) from (Linné) from Porugal Portugal transmit Protostrongylus Protostrongylus linearis, a nematode parasite of rufescens, another livestock. It has been nematode parasite of intercepted on wood livestock. It has been packing material for tiles intercepted many times on cut flowers, plants for propagation, on wood packing material for tiles, on and in containers Monacha obstructa (Pfeiffer) Monacha syriaca (Ehrenberg) transmit several species is a vector of the sheep trematode Brachylaima, lungworm Cystocaulus causing brachylaimiasis, a ocreatus. The species is disease of the human frequently intercepted on cut gastro-intestinal tract in flower, on tiles, and in and on Egypt. The species is containersfrom several frequently intercepted on cut countries in the Middle East flowers and edible herbs and Turkey from several countries in the Middle East, especially Israel Numerous snail species , including the giant African snail GAS transmit numerous species of Phytophthora, which attacks dicotyledon plants, many of which are of enormous economic and environmental value  Numerous terrestrial and freshwater snails are vectors of a wide variety of nematodes, trematodes and cestodes that can infect humans and livestock  Others are secondary hosts of serious disease-causing nematodes such as the species of Angiostrongylus  When handling live snails or slugs, whether in the field conducting surveys or dealing with them in the lab, it is advisable to wear protective gloves, making a conscious effort NOT to touch your face inadvertantly, especially eyes, nose and mouth while doing so  ALL CBP and PPQ agricultural inspectors wear gloves as standard practice during their inspections  After removing gloves, wash your hands with hot soapy water, and then use a ethanol- based hand cleanser Richard Hoenisch (WPDB) at U.C. Davis  Suzete Gomes, Samanta Singh and Francisco Borrero (USDA National Malacology Laboratory)  Greg Bartman, Patrick Marquez, William Tang and Frederick Zimmerman (USDA Port Identifiers / Malacology Specialists)

Lissachatina fulica massing in Saint Lucia Lesser Antilles (photo: D. G. Robinson)